JPH04321435A - Torque distribution mechanism of differential device - Google Patents

Abstract

PURPOSE:To construct a torque distribution mechanism in small size, which is to control any as desired the distributing proportion of the torque transmitted from one input element of a differential device to its two output elements. CONSTITUTION:A planetary carrier 8 as one of the output elements of a differential device D is coupled with a right shaft 9, while a sun gear 5 as the other output element is coupled with the left shaft 10. A planetary carrier 12 of this torque distribution mechanism 11 of planetary gearing type is coupled with the left shaft 10, and external cogs 17 of a ring gear 15 are interlocked with the external cogs of the first named planetary carrier 8 with a certain reduction ratio through a pair of spur gears 18, 19, and a sun gear 14 is rotated by a motor 20. Use of spur gears 18, 19 instead of bevel gears for coupling the differential device D with the torque distribution mechanism 11 permits shortening the axial direction dimension of the mechanism 11.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a differential device having one input element and two output elements, in which torque applied to the input element of the differential device is distributed to the two output elements at a predetermined ratio. The present invention relates to a torque distribution mechanism for a differential device.

0002

[Prior Art] A differential device installed in the power transmission system of an automobile is configured to absorb the difference in rotational speed that occurs between the left and right wheels when the automobile turns, and distribute engine torque to the left and right wheels in an appropriate ratio. be done. However, general differentials operate based on the difference in the load applied to the left and right wheels, so if one wheel runs onto a road surface with a low coefficient of friction and spins, the amount of torque transmitted to the other wheel will be reduced. There is a problem that the torque transmission may be reduced or the torque transmission may be interrupted.

In order to avoid such inconveniences, a differential device has been developed that actively controls the differential device based on the rotation angle of the steering wheel and the vehicle speed, and distributes torque to the left and right wheels appropriate for the current driving condition. Torque distribution mechanisms have been proposed.

FIG. 7 shows the structure of a torque distribution mechanism of such a conventional differential gear. In the figure, a propeller shaft 01 connected to and driven by an engine E and a transmission M is connected to a bevel gear 02 and a bevel gear 03.
is transmitted to the central shaft 04 via. A right shaft 05R that drives the right wheel WR and a left shaft 05L that drives the left wheel WL are coaxially arranged on the left and right sides of the central shaft 04, and the central shaft 04 and the right shaft 05R
A right differential DR is provided between the central shaft 04 and the left shaft 05L, and a left differential DL is provided between the central shaft 04 and the left shaft 05L.

Both differential devices DR and DL are of the planetary gear type, and include planetary carriers 06R and 06L fixed to the right shaft 05R and the left shaft 05L, respectively, and each planetary carrier 06R.
, 06L, the planetary gear 07 is rotatably supported by
R, 07L, a pair of left and right sun gears 08R, 08L fixed to the central shaft 04 and meshing with each planetary gear 07R, 07L, and each planetary gear 07
A pair of left and right ring gears 09R meshing with R and 07L
,09L. A pair of left and right bevel gears 010R, 010L formed integrally with the left and right ring gears 09R, 09L is a common bevel gear 0 driven by a motor 011 via a reduction gear 012.
It meshes with 13.

According to the torque distribution mechanism having the above structure, the torque transmitted to the central shaft 04 is transmitted to both differential gears DR.
, DL to the right wheel WR and the left wheel WL, the left and right ring gears 09R, 09L
That is, the left and right bevel gears 010R and 010L do not rotate. However, if there is a difference in the loads applied to the right wheel WR and the left wheel WL, the right shaft 05R and the left shaft 05L
As a result, a rotational speed difference also occurs between the left and right ring gears 09R and 09L. Therefore, if the motor 011 actively applies a rotational speed difference to the left and right bevel gears 010R and 010L, that is, the left and right ring gears 09R and 09L, through the common bevel gear 013, the center shaft 04 to the right shaft 05
The distribution ratio of the torque transmitted to R and the left shaft 05L can be arbitrarily controlled.

[0007]

Problems to be Solved by the Invention However, the torque distribution mechanism of the conventional differential device described above is limited to the left and right ring gears.
A pair of left and right bevel gears 010R, 010L for giving a rotational speed difference to R, 09L and the bevel gear 01
Common bevel gear 013 that meshes with 0R and 010L
is essential, and therefore there is a problem in that the axial dimension of the torque distribution mechanism increases.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to downsize the torque distribution mechanism of a differential gear by eliminating the bevel gear.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a differential device having one input element and two output elements, in which the torque applied to the input element of the differential device is A torque distribution mechanism for a differential device that distributes torque to two output elements at a predetermined ratio, comprising a planetary gear mechanism including a ring gear, a sun gear, and a planetary carrier that supports a planetary gear that meshes with the ring gear and the sun gear, A first feature is that the planetary carrier is coupled to the one output element, the ring gear is coupled to the other output element via a spur gear, and the sun gear is connected to a drive source.

[0010] In addition to the above-mentioned first feature, the present invention also has the following features:
A second feature is that the differential device includes a ring gear, a sun gear, and a planetary carrier that supports a planetary gear that meshes with the ring gear and the sun gear.

[0011] In addition to the above-mentioned first feature, the present invention also has the following features:
A third feature is that the drive source and the sun gear are connected via a transmission means that restricts rotation of the sun gear when power is transmitted from the sun gear to the drive source.

[0012] In addition to the above-mentioned first feature, the present invention also has the following features:
A fourth feature is that the drive source is arranged coaxially with the rotation axis of the sun gear.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 shows a differential torque distribution mechanism according to a first embodiment of the present invention applied to a front engine/front drive vehicle. As shown in the figure, a transmission M is connected to an engine E mounted horizontally on the vehicle body, and a differential input shaft 1, which is the output shaft of the transmission M, supplies driving force to a planetary gear type differential D. An input gear 2 for transmission is provided.

The differential device D includes a ring gear 4 having an external gear 3 on its outer periphery that meshes with the input gear 2 of the differential device input shaft 1, and a sun gear 5 coaxially disposed inside the ring gear 4. It is comprised of a planetary carrier 8 that supports an outer planetary gear 6 that meshes with the ring gear 4 and an inner planetary gear 7 that meshes with the sun gear 5 in a state where they mesh with each other. The differential device D is
The ring gear 4 functions as an input element, and
Planetary carrier 8, which functions as one output element, is connected to right wheel WR through right shaft 9, and sun gear 5, which functions as the other output element, is connected to left wheel WL through left shaft 10.

Next, the structure of the torque distribution mechanism 11 that distributes the torque input from the ring gear 4, which is the input element of the differential device D, to the planetary carrier 8 and the sun gear 5, which are the two output elements, at a predetermined ratio will be explained. do.

The torque distribution mechanism 11 includes a planetary gear mechanism P, and a planetary carrier 12 connected to the left shaft 10.
A planetary gear 13 provided on the left shaft 10 meshes with a sun gear 14 relatively rotatably supported, and the planetary gear 13 meshes with a ring gear 15 disposed on the outer periphery of the planetary carrier 12. Differential device D
External gear 16 integrally formed with planetary carrier 8 of
The external gear 17 formed on the ring gear 15 of the planetary gear mechanism P meshes with pinions 18 and 19 as a pair of integrally formed spur gears, so that the differential device D and the planetary gear mechanism P are mutually connected. Concatenated.

Now, if the numbers of teeth of the planetary carrier 12, sun gear 14, and ring gear 15 of the planetary gear mechanism P are respectively ZC, ZS, and ZR, and the rotational speeds are respectively ωC, ωS, and ωR, then the sun gear 14
When fixed (i.e., ωS = 0), as is well known, ωR = ωC × (1+ZS /ZR
)...■ holds true.

Now, considering the case where the right wheel WR and the left wheel WL rotate at the same speed, the rotational speed of the planetary carrier 12 of the planetary gear mechanism P that rotates together with the left wheel WL is ωC as described above, The rotational speed of the planetary carrier 8 of the differential device D, which rotates integrally with the right wheel WR which has the same speed as the left wheel WL, also becomes ωC. The rotational speed ωR of the ring gear 15 driven by the planetary carrier 12 of the planetary gear mechanism P is expressed as ωC×(1+ZS/ZR) according to the equation (2) above.

That is, in order for the right wheel WR and the left wheel WL to rotate at the same speed ωC, the rotation speed of the planetary carrier 8 of the differential device D becomes ωC, and the rotation speed of the ring gear 15 of the planetary gear mechanism P becomes ωC× (1+ZS
/ZR), the pair of pinions 18,1
It is necessary to interlock the planetary carrier 8 and ring gear 15 with each other by means of 9. To do this, the radius r1 of the external gear 17 formed on the ring gear 15 and the radius r2 of the external gear 16 formed on the planetary carrier 8 are determined as follows: r2 /r1 =1+(ZS /ZR)...■
It is sufficient to set it so that the following relationship is satisfied.

[0021] A planetary gear mechanism input gear 22, which is integrally formed with the sun gear 14 of the planetary gear mechanism P, is rotated by the pinion 21 of the electric motor 20, which is driven based on the rotation angle of the steering wheel of the vehicle, the vehicle speed, etc. Driven.

Next, the operation of the first embodiment of the present invention having the above-described configuration will be explained.

While the vehicle is traveling straight, the motor 20 is held in a stopped state, and the sun gear 14 of the planetary gear mechanism P, which is connected to the pinion 21 of the motor 20 via the planetary gear mechanism input gear 22, is fixed. At this time, the planetary carrier 8 of the differential device D and the planetary carrier 12 of the planetary gear mechanism P are connected to the ring gear 15 and the external gear 17 as described above.
, pinion 19, pinion 18, and externally toothed gear 16 at a predetermined gear ratio. Therefore, the rotational speeds of both planetary carriers 8 and 12, that is, the rotational speeds of the planetary carrier 8 and the sun gear 5, which are a pair of output elements of the differential device D, are forced to match.
The right wheel WR and the left wheel WL rotate at the same speed.

Now, when the steering wheel is operated to turn the vehicle, the required rotational speed difference between the left and right wheels WR, WL is calculated based on the steering angle and the vehicle speed, and the direction and direction corresponding to the rotational speed difference are calculated. Motor 2 at speed
0 is driven. As a result, the sun gear 14 of the planetary gear mechanism P rotates, and a predetermined difference occurs between the rotational speeds of both planetary carriers 8 and 12, that is, the rotational speeds of the planetary carrier 8 and the sun gear 5 of the differential device D. Thus, the torque transmitted from the mission M to the ring gear 4 of the differential device D is transmitted to the left and right wheels WR and WL at a predetermined ratio determined by the rotational direction and rotational speed of the motor 20.

[0025] Then, this differential device D and the planetary gear mechanism P
Since these are connected by pinions 18 and 19 made of spur gears, the axial dimension of the torque distribution mechanism can be shortened compared to a conventional mechanism using bevel gears.

FIG. 2 shows a second embodiment of the present invention.
This embodiment is characterized in that a hydraulic motor 20 is used as the drive source for the sun gear 14 of the planetary gear mechanism P, and a hydraulic pressure generation source 23 is connected to the motor 20. Hydraulic pressure source 2
3 is a hydraulic pump driven by an electric motor;
An appropriate hydraulic pump such as a hydraulic pump driven by the engine E, a hydraulic pump provided in the power transmission system from the engine E to the wheels WR, WL, etc. can be used.

FIG. 3 shows a third embodiment of the present invention.
In this embodiment, a hydraulic pump 24 and a hydraulic motor 20 are integrally combined on the differential gear input shaft 1, which is the output shaft of the mission M.
0 is of variable capacitance type. According to this embodiment, the rotational speed of the sun gear 14 of the planetary gear mechanism P can be controlled by changing the capacity of the hydraulic pump 24 or the hydraulic motor 20.

FIG. 4 shows a fourth embodiment of the present invention.
This embodiment is characterized in that the planetary gear mechanism input gear is constituted by a worm wheel 25, and a worm gear 26 provided on the electric motor 20 is meshed with the worm wheel 25. According to this embodiment, the transmission mechanism consisting of the worm gear 26 and the worm wheel 25 allows the transmission of driving force from the motor 20 to the planetary gear mechanism P without any problem.
Transmission of the driving force to zero is blocked. Therefore, the right wheel W
When either R or the left wheel WL slips, the excessive load input from the planetary gear mechanism P to the motor 20 is received by the worm gear 26, so the motor 20 can be downsized.

FIG. 5 shows a fifth embodiment of the present invention.
In this embodiment, a sun gear 14 of a planetary gear mechanism P supported by a left shaft 10 so as to be relatively rotatable is directly connected to an output shaft 27 of a motor 20 and driven. For that purpose motor 20
The output shaft 27 is formed hollow, and the left shaft 10 passes through the inside thereof. According to this embodiment, the radial dimension of the torque distribution mechanism 11 can be reduced in size.

FIG. 6 shows a sixth embodiment of the present invention.
This embodiment is characterized in that a common bevel gear type differential device D is used. That is, this differential device D includes a differential case 29 that has an external gear 28 on its outer periphery that meshes with the input gear 2 and is rotatably supported by the right shaft 9 and the left shaft 10, and a It is composed of a supported differential pinion 30 and a pair of differential side gears 31 and 32 that mesh with the differential pinion 30 and are connected to the right shaft 9 and the left shaft 10, respectively. The external gear 16 provided in the differential case 29 is connected to the planetary gear mechanism P via pinions 18 and 19 as in the first embodiment described above. In this embodiment, the differential case 29 functions as an input element, and the pair of differential side gears 31 and 32 function as output elements.

[0031] Also in this sixth embodiment, the differential device D and the planetary gear mechanism P are connected to the pinion 1 consisting of a spur gear.
8 and 19, the axial dimension of the torque distribution mechanism 11 can be reduced compared to a conventional bevel gear.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and various small design changes can be made without departing from the scope of the invention described in the claims. It can be performed.

For example, in the planetary gear type differential device D according to the first to fifth embodiments, the ring gear 4, the sun gear 5,
And which of the planetary carriers 8 is used as an input element or an output element can be changed as appropriate. Furthermore, the torque distribution mechanism of the present invention is applicable not only to the front wheel drive system of a vehicle but also to the rear wheel drive system, and is also applicable to torque distribution between the front wheels and rear wheels of a four-wheel drive vehicle.

[0034]

As described above, according to the first feature of the present invention, the differential gear and the planetary gear mechanism of the torque distribution mechanism are connected via a spur gear having a thin thickness in the axial direction of the torque distribution mechanism. Therefore, the size can be reduced compared to a conventional torque distribution mechanism using a bevel gear whose rotating shaft is orthogonal to the axial direction.

According to a second feature of the present invention, the differential device is a planetary gear type consisting of a ring gear, a sun gear, and a planetary carrier that supports a planetary gear that meshes with the ring gear and the sun gear, so that a bevel gear is not required. , the axial dimension of the torque distribution mechanism can be reduced in size compared to the case where a bevel gear type differential device is adopted.

According to the third feature of the present invention, reverse transmission of power from the sun gear of the planetary gear mechanism to the drive source is regulated, thereby preventing excessive load from being applied to the drive source. As a result, it becomes possible to use a small, lightweight, and low output drive source.

According to the fourth feature of the present invention, since the drive source is arranged coaxially with the rotation axis of the sun gear, the radial dimension of the torque distribution mechanism can be reduced in size.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a torque distribution mechanism of a differential gear according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a torque distribution mechanism of a differential gear according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a torque distribution mechanism of a differential gear according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a torque distribution mechanism of a differential gear according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a torque distribution mechanism of a differential gear according to a fifth embodiment of the present invention.

FIG. 6 is a diagram showing a torque distribution mechanism of a differential gear according to a sixth embodiment of the present invention.

[Figure 7] Diagram showing the torque distribution mechanism of a conventional differential gear

[Explanation of symbols]

4...Ring gear (input element) 5...Sun gear (output element) 6...Outer planetary gear (planetary gear) 7
...Inner planetary gear (planetary gear) 8.
... Planetary carrier (output element) 12 ... Planetary carrier 13 ... Planetary gear 14 ... Sun gear 15 ... Ring gear 18 ... Pinion (spur gear) 19 ... Pinion (spur gear) 20 ... Motor (drive source) 25... Worm wheel (transmission mechanism) 26... Worm gear (transmission mechanism) D... Differential device P... Planetary gear mechanism

Claims (4)

[Claims] 1. In a differential (D) with one input element (4) and two output elements (5, 8), the torque applied to the input element (4) of the differential (D) 2
A torque distribution mechanism of a differential device that distributes the torque to two output elements (5, 8) at a predetermined ratio, the torque distribution mechanism including a ring gear (15);
A planetary gear mechanism (P) includes a sun gear (14), and a planetary carrier (12) that supports a planetary gear (13) that meshes with the ring gear (15) and the sun gear (14). coupled to one output element (5), the ring gear (15) is coupled to the other output element (8) via spur gears (18, 19), and the sun gear (
14) is connected to the drive source (20),
Differential torque distribution mechanism. 2. The differential device (D) is a ring gear (4).
, a sun gear (5), and a planetary carrier (8) that supports planetary gears (6, 7) meshing with the ring gear (4) and the sun gear (5). Torque distribution mechanism. 3. Transmission means (25) for controlling rotation of the sun gear (14) when power is transmitted from the sun gear (14) to the drive source (20). 26). The torque distribution mechanism for a differential gear according to claim 1, wherein the torque distribution mechanism is connected via a. 4. The torque distribution mechanism for a differential gear according to claim 1, wherein the drive source (20) is arranged coaxially with the rotation axis of the sun gear (14).